Here is some more gun ideas I have that I was thinking about.
Assault Rifles: M16A3, SIG SG 550, AEK 971, SCAR-H
SMGs: MSMC, QCW-05, PP-2000
LMGs: M249, QBB-95, Ultimax 100,
Shotguns: High Standard Model 10, TOZ-194, Ranger
Sniper Rifles: PSG1, XM2010, Gepard anti-material rifle
Handguns: M9-T, Colt SOCOM, AMT AutoMag V
Machine Pistols: TMP, PDW,Claridge Hi-Tec
Launchers: FIM-43 Redeye, LAW 80, LRAC F1
Also if you don't know what the M9-T is well the T means tranquilizer and my idea is if you get shot by the gun it will hinder your vision and stun you for 25 seconds.
MW3 can't do Weapon DLC due to limited RAM.
These sound like pretty good ideas. What we can do for you is have your ideas forwarded to the appropriate parites for consideration, Thank you for taking the time to leave some great feedback.